Anthropometric Estimations for Iranian General Population.

Background
An essential requirement exists for a single exhaustive source of anthropometric databank in Iran. Available information about Iranian bodily dimensions is not applicable to the general population due to the sample of people investigated. This study aimed to present the first Iranian anthropometric databank by estimation.


Methods
After a systematic review, 24 relevant sources of information were found and included. No time limit was considered. The method of Rapid Anthropometrics Scaled for Height was used.


Results
Overall, 36 bodily dimensions were estimated, for which the seven percentiles of 1st, 5th, 25th, 50th, 75th, 95th, and 99th were calculated, stratified by sex.


Conclusion
The resulting tables can be claimed as the most representative anthropometric databank for Iranian general 20-64 yr population now. Data are suitable for practical purpose and are applicable in both occupational and community setting.


Introduction
The main principle of ergonomics is to design the activity to match the characteristics of the user. On the other word, if an instrument, a workplace or a system is intended for human use, then its design should be based upon the characteristics of its human users. This principle, so-called "user-centered design", could result in many enhancements in terms of functional efficiency, comfort, health, safety and quality of life (1). In contrast, the lack of incorporating anthropometric information in the design phase would result in an increase in the frequency of work-related injuries, as well as a decrease in human performance and well-being. However, human beings are not all the same. Their anthropometric (e.g. body size, shape strength, and endurance), physiological, Biome-chanical and psychological characteristics differ from one to another. In addition, factors such as age, sex, race, job, diet, physical exercise and so on influence human body dimensions (1,2). These variabilities need to be taken into account by designers in order to provide adequate adjustability of workstations, tools, products and human-machine interfaces. Because of the above mentioned human inter and intra-individual changes, the majority of developed and developing countries have produced their own anthropometric databank. Some examples include anthropometric data of Asian (3,4), African (5,6), European (7,8) and American (9,10) peoples. However, although publication of the first systematic anthropometric tables dated on 1950s, no anthropometric survey has yet been conducted on Iranian general population with regard to the occupational health application. Available data on this topic is mainly limited to Iranian industrial (11) and army (12) personnel which would not be presentative for the general population. Apart from its vital importance for designing various work stations and spaces, national anthropometric tables are required to fabricate any ease of use urban spaces such as public buildings, leisure facilities, general transportation services, and so on. Since anthropometric surveys are often costly and time-consuming, ergonomists prefer to prepare anthropometric databases based on more simple methods such as estimation rather than measurement. One of the most widely employed methods of estimation is that proposed by Barkla (13) and Roebuck et al. (14). Entitled "Rapid Anthropometrics Scaled for Height" (RASH) by Pheasant, this method was validated and employed to estimate British anthropometric database (15,16). The RASH method requires only data on the stature (i.e. mean and standard deviation) of an unknown population to which scaling factors derived from a known homogeneous population is applied. The technique was used in some similar researches afterward all over the world (17,18). An important need for appropriate anthropometric source on Iranian body characteristics exists among national ergonomists and designers. Recently, existed anthropometric data for Iranian population is not sufficiently comprehensive with respect to both sample size and representativeness (19). Therefore, the present study is the first attempt to provide a single comprehensive and representative source of anthropometric information on Iranian general population. Such databank is extensively applicable as a key element to provide ergonomic design requirements and to create products, hand tools, furniture, workstations, etc. as much fit as possible to the nation. In this regard, after an integrated review of related published literature, a dataset is assembled using the RASH method assumed to be sufficiently exhaustive and accurate for practical purpose; especially in terms of the creation of spaces in various public or industrial environments.

Materials and Methods
The method of RASH was applied for estimating anthropometric database of Iranian general population. This method is based on the assumption that although people vary greatly in size, they are likely to be similar in proportions (2). It requires only know the mean (m) and standard deviation (s) of stature of an unknown population (i.e. target population). Scaling factors for intended bodily dimensions would be calculated from a known population (i.e. reference population) and then applied to the height data in the target one. Coefficient em was calculated using following formula (15): em= x ̅ h ̅ Where x̅ is the mean value of the intended bodily dimension and h̅ is the mean stature in the reference population. Then, scaling ratio (Em) was obtained as arithmetic mean of em (15,16): Em= ∑em n The same method was used for estimating coefficients (es) and scaling ratios (Es) related to the standard deviations. Calculations were made as a function of sex.

The reference population
Conducting a systematic review using Google Scholar, Medline, SID, IranMedex, Magiran, MedLib and Civilica, an integrative collection of ever published anthropometric datasets of Iranian adults was developed. No time limit was considered. This collection was considered as the reference population. Studies were included as a function of their aim and methodology. Therefore, cases hypothesized any relationship between body variables (e.g. weight, BMI, wrist circumferences, etc.) and health problems (obesity, diseases, etc.) or conducted on children were excluded. Repeated datasets (i.e. same data published in more than one source) were also removed. As presented in Table 1, altogether 24 sources of information were found.

The target population
For the target population, we have selected recent nationwide surveillance on noncommunicable disease risk factors, which in our knowledge is the best representative of the general population in terms of sample size, age, sex, socio-economic, and geographical distribution. Using a random multistage cluster sampling method, the study measured, among other variables, stature of 79,611 Iranian rural and urban citizens (50.1% men; 49.9% women) aged from 20 to 64 yr with standardized and calibrated instruments (20).

Results
Scaling factors for 36 anthropometric estimations are presented in Table 2. Accordingly, stature has the highest ratios with eye and shoulders heights; and the smallest ratios with hand and foot breadths. Indeed, body dimensions of men and women are likely to follow a similar scaling profile (Table 2). Tables 3 and 4 show anthropometric estimates calculated based on these scaling factors for men and women, respectively. Iranian men's average height is estimated to be 1697 mm versus 1564 mm for female. The tallest Iranian man is about 348 mm taller than the shortest one; while the tallest Iranian woman is about 317 mm taller than the shortest woman is.
In the case of previously reported Iranian anthropometric datasets, one of the limitations face to the representativeness of data is that the sample size for about 80% of them is under 500 (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39). Moreover, being conducted on the specified groups of industrial (11,33,39) or army (12,30,40) employees or in a specified location (32,35), not across Iran, is the fact supporting the inaccuracy of using previous datasets for the general population. Anthropometric dimensions significantly differ between various occupational groups (41). Incorrect design of workplaces and prod-ucts due to the lack of having access to an appropriate source of anthropometric databank could cause work-related physiological damages because of prolonged exposure to awkward postures. This could at least partly explain the high prevalence of musculoskeletal disorders in different Iranian industrial and nonindustrial sectors (42)(43)(44)(45). Anthropometric dimensions should also be taken into consideration in the design of urban spaces such as public buildings, restaurants, hospitals and so on in order to provide an environment that supports the majority of residents especially with respect to some aspects such as clearance and reach. Hip breadth  261  287  324  350  375  413  439  38  20  Chest depth  162  183  214  235  256  287  308  31  21  Abdominal depth  100  142  203  245  287  347  390  62  22  Shoulder elbow length  218  250  295  326  357  402  434  46  23  Elbow fingertip length  335  357  388  409  430  461  483  32  24  Upper limb length  573  610  662  697  733  785  822  53  25  Shoulder grip length  453  491  545  583  620  674  712  56  26  Head length  76  105  148  177  206  248  278  43  27  Head breadth  51  76  112  136  161  197  222  37  28  Hand length  95  116  147  168  189  219  240  31  29  Hand breadth  30  41  58  69  80  96  108  17  30  Foot length  190  200  216  226  236  252  262  16  31  Food breadth  53  62  74  83  91  103  112  12  32 Vertical grip reach (standing)  1474  1591  1758  1874  1989  2156  2273  172  33 Vertical grip reach (sitting)  999  1035  1088  1124  1159  1212  1248  54  34  Forward grip reach  489  538  608  656  704  774  823  72  35  Span  312  337  372  397  421  456  481  36  36  Elbow span  287  321  369  402  435  484  517  49 Some key anthropometric dimensions are "knee height", "sitting height" and "arms reach" (1). A good anthropometric database should also be up-to-date. This feature is essential since human body characteristics vary over time and from generation to another. Our proposed set of estimations has the potential of being rapidly updated as soon as a more recent source of Iranian height would be available. Indeed, these data could be easily repeated for any sub-group of the general population. Errors associated with using this technique are small and would be considered as negligible, even in comparison with common interpretation errors or those arising from the corrections for shoes and cloths (16). However, one could sug-gest that this method is much better applicable to body dimensions which best depend on the length of bones than circumferential dimensions. If relevant, this may be considered as a limitation of this study.

Conclusion
Even though estimated data should be employed with prudence, but data prepared with this method is sufficiently reliable for many purposes (15). The application of the present anthropometric databank would be beneficial to better match the numerous manmade products and spaces with individual users. Therefore, a better match between national designs and Iranian users; as well as a more accurate evaluation of all products, machinery and spaces, either national or imported international ones, is expected. By means of integrating the presented tables into design phase, we hope national designers to provide greater safety, satisfaction and commonwealth for Iranian citizens.